Solid electrolytic capacitor

ABSTRACT

A solid electrolytic capacitor that includes a capacitor element including an anode portion having a metal layer, a dielectric layer, and a cathode portion having a solid electrolyte layer and a current collector layer; a leading conductor layer; an insulating resin body covering the capacitor element and the leading conductor layer, the insulating resin body having a first end surface and a second end surface opposite to each other; a first external electrode; and a second external electrode. The first external electrode has at least one plating layer on the first end surface, and is connected to the leading conductor layer at the first end surface. The second external electrode has at least one plating layer on the second end surface, and is connected to the metal layer at the second end surface.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Japanese Patent ApplicationNo. 2016-118972, filed Jun. 15, 2016, Japanese Patent Application No.2016-118973, filed Jun. 15, 2016, Japanese Patent Application No.2016-118975, filed Jun. 15, 2016, Japanese Patent Application No.2017-112109, filed Jun. 6, 2017, and Japanese Patent Application No.2017-115327, filed Jun. 12, 2017, the entire contents of each of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a solid electrolytic capacitor.

Description of the Background Art

A solid electrolytic capacitor described in International PublicationNo. 2013/088954 includes a stack of a plurality of capacitor elements,an anode terminal bonded to a side surface of the stack, and a cathodeterminal bonded to a portion of a main surface of the stack and a sidesurface of the stack. The stack is also entirely covered with resin.

SUMMARY OF THE INVENTION

In the solid electrolytic capacitor described in InternationalPublication No. 2013/088954, the anode terminal and the cathode terminalare each drawn out from the center of the stack in the stackingdirection to an outside of the resin and thus routed outside the resinto face one main surface of the stack. Even with such a configuration,there is still the need for further reducing the solid electrolyticcapacitor's ESR (Equivalent Series Resistance) and ESL (EquivalentSeries Inductance). In addition, there is a need to reduce the size ofthe solid electrolytic capacitor's external shape.

Further, the solid electrolytic capacitor disclosed in InternationalPublication No. 2013/088954 is configured such that the anode terminaland the cathode terminal are partially buried in a resin layer. In sucha configuration, for the purpose of miniaturization, a change is madesuch that a plurality of capacitor elements have an anode side exposedat an end surface on the side of one end of the resin and an externalelectrode for the anode is provided on the end surface of the resin byplating or the like so as to cover the end surface while the externalelectrode is brought into contact with the exposed portion of the anodeside of the capacitor element. Simultaneously, a leading conductor for acathode connected to the stack is also exposed at an end surface of theother end side of the resin and an external electrode for the cathode isprovided on the end surface of the resin by plating or the like so as tocover the end surface while the external electrode is brought intocontact with the exposed portion of the end portion of the leadingconductor.

In such a case, after the plurality of capacitor elements and theleading conductor layer are molded with resin, the resin mold is cut toexpose the capacitor elements' anode side and expose the end portion ofthe leading conductor layer. If an external electrode is formed toextend from an end surface to a main surface without processing of anend surface (or cut surface) of the cut resin mold, the externalelectrode poorly adheres and tends to peel off at a boundary between theend surface of the resin and the main surface of the resin. As a result,an electric resistance between a portion of the external electrodeprovided on the end surface and a portion of the external electrodeprovided on the main surface is increased.

The present invention has been made in view of the above problems, andan object of the present invention is to provide a compact solidelectrolytic capacitor with reduced ESR and ESL.

Another object of the present invention is to provide a compact solidelectrolytic capacitor maintaining reliability.

A further object of the present invention is to provide a solidelectrolytic capacitor capable of suppressing peeling of an externalelectrode provided on an end surface of a resin body in which acapacitor element is buried.

A solid electrolytic capacitor based on an aspect of the presentinvention comprises at least one capacitor element including an anodeportion composed of a metal layer extending in a first direction andhaving an external surface provided with a plurality of recesses, adielectric layer provided on the external surface of the metal layer,and a cathode portion having a solid electrolyte layer provided on thedielectric layer and a current collector layer provided on the solidelectrolyte layer; a leading conductor layer electrically connected tothe current collector layer; an insulating resin body covering thecapacitor element and the leading conductor layer, the insulating resinbody having a first end surface and a second end surface opposite toeach other. The first external electrode has at least one plating layeron the first end surface, and is connected to the leading conductorlayer at the first end surface. The second external electrode has atleast one plating layer provided on the second end surface, and isconnected to the metal layer at the second end surface.

In the solid electrolytic capacitor, preferably, a plurality ofconductive particles are present in each of the first end surface andthe second end surface.

In the solid electrolytic capacitor the conductive particles preferablycontain Pd.

In the solid electrolytic capacitor, the at least one plating layer ofthe first external electrode preferably includes a first plating layeron the first end surface, a second plating layer on the first platinglayer, and a third plating layer on the second plating layer, and the atleast one plating layer of the second external electrode preferablyincludes a fourth plating layer on the second end surface, a fifthplating layer on the fourth plating layer, and a sixth plating layer onthe fifth plating layer. Preferably, each of the first and fourthplating layers contain Cu, the second and fifth plating layers containNi, and the third and sixth plating layers contain Sn.

In the solid electrolytic capacitor of the present invention, the metallayer preferably contains Al.

In the solid electrolytic capacitor of the present invention, thedielectric layer is preferably composed of an oxide of Al.

In a further aspect of the present invention, an external surface of thedielectric layer located on a side opposite to that of the cathodeportion and free of the solid electrolyte layer, and provided on anexternal surface of the metal layer closer to the second end surface, ispreferably covered with an insulating resin layer different incomposition from the insulating resin body.

Preferably, a length of the insulating resin layer in the firstdirection is preferably equal to or greater than a length of theinsulating resin body in the first direction multiplied by 0.025 andequal to or less than the length of the insulating resin body in thefirst direction multiplied by 0.5.

In the solid electrolytic capacitor, the insulating resin layer ispreferably 5 μm to 30 μm in thickness.

The insulating resin layer also preferably includes polyimide resin orpolyamide imide resin.

In the solid electrolytic capacitor based on another aspect of thepresent invention, an end surface of the metal layer closer to thesecond end surface is preferably covered with a first plating filmcontaining Zn and the first plating film is preferably covered with asecond plating film containing Ni. Furthermore, the second externalelectrode is preferably indirectly electrically connected to the metallayer. In that case, the first plating film and the second plating filmare preferably provided between the second external electrode and themetal layer.

The solid electrolytic capacitor based on yet another aspect of thepresent invention preferably comprises a plurality of capacitorelements. Furthermore, the plurality of capacitor elements arepreferably stacked in a second direction orthogonal to the firstdirection, with mutually adjacent capacitor elements having theirrespective current collector layers electrically connected to eachother. In that case, the current collector layer of only one capacitorelement of the plurality of capacitor elements that is adjacent to theleading conductor layer is electrically connected to the leadingconductor layer.

In the solid electrolytic capacitor, the first end surface and thesecond end surface preferably have a surface roughness (Ra) of 2.2 μm to8.3 μm.

In the solid electrolytic capacitor based on a further aspect of thepresent invention, the insulating resin body preferably further has afirst main surface and a second main surface opposite to each other in asecond direction orthogonal to the first direction, and a first sidesurface and a second side surface opposite to each other in a thirddirection orthogonal to the first direction and the second direction.Furthermore, the insulating resin body preferably has a first connectingportion connecting the first end surface and the first main surface, asecond connecting portion connecting the first end surface and thesecond main surface, a third connecting portion connecting the secondend surface and the first main surface, and a fourth connecting portionconnecting the second end surface and the second main surface.Furthermore, the first external electrode is preferably provided so asto extend from at least the first end surface to the first main surfaceand the second main surface across the first connecting portion and thesecond connecting portion, and the second external electrode ispreferably provided so as to extend from at least the second end surfaceto the first main surface and the second main surface across the thirdconnecting portion and the fourth connecting portion. In that case, thefirst connecting portion, the second connecting portion, the thirdconnecting portion, and the fourth connecting portion each have a firstchamfered portion.

In the solid electrolytic capacitor based on an additional aspect of thepresent invention, the first chamfered portion may have a bent shape ina cross-sectional view as seen in the third direction.

In the solid electrolytic capacitor based on another aspect of thepresent invention, the first chamfered portion may have a curved shapein a cross-sectional view as seen in the third direction.

In the solid electrolytic capacitor, a radius of curvature of the firstchamfered portion of the first and third connecting portions ispreferably larger than a radius of curvature of the first chamferedportion of the second and fourth connecting portions.

In the solid electrolytic capacitor based on an additional aspect of thepresent invention, the insulating resin body preferably includes a firstinsulating resin portion on a side of the first main surface and whichdefines the first main surface, and a second insulating resin portion ona side of the second main surface and which defines the second mainsurface. In that case, the second insulating resin portion is preferablymade of a material harder than that of the first insulating resinportion. Furthermore, the first chamfered portion of the first and thirdconnecting portions is preferably rounder than the first chamferedportion of the second and fourth connecting portions.

In the solid electrolytic capacitor based on another aspect of thepresent invention, the insulating resin body may have a fifth connectingportion connecting the first end surface and the first side surface, asixth connecting portion connecting the first end surface and the secondside surface, a seventh connecting portion connecting the second endsurface and the first side surface, and an eighth connecting portionconnecting the second end surface and the second side surface. In thatcase, the first external electrode preferably extends from the first endsurface across the first connecting portion, the second connectingportion, the fifth connecting portion, and the sixth connecting portionto the first and second main surfaces and the first and second sidesurfaces, and the second external electrode preferably extends from thesecond end surface across the third connecting portion, the fourthconnecting portion, the seventh connecting portion, and the eighthconnecting portion to the first and second main surfaces and the firstand second side surfaces. Furthermore, the fifth connecting portion, thesixth connecting portion, the seventh connecting portion, and the eighthconnecting portion preferably each have a second chamfered portion.

In the solid electrolytic capacitor, the second chamfered portion mayhave a bent shape in a cross-sectional view as seen in the seconddirection.

In the solid electrolytic capacitor, the second chamfered portion mayhave a curved shape in a cross-sectional view as seen in the seconddirection.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a solid electrolytic capacitor accordingto an embodiment.

FIG. 2 is a cross-sectional view of the solid electrolytic capacitortaken along a line II-II shown in FIG. 1.

FIG. 3 is an enlarged cross-sectional view of a portion III shown inFIG. 2.

FIG. 4 is a cross-sectional view taken along a line IV-IV shown in FIG.2.

FIG. 5 is a front view of a first end surface of a solid electrolyticcapacitor according to the embodiment.

FIG. 6 is a front view of a second end surface of the solid electrolyticcapacitor according to the embodiment.

FIG. 7 is a bottom view of the solid electrolytic capacitor according tothe embodiment.

FIG. 8 is a flowchart of producing a solid electrolytic capacitoraccording to the embodiment.

FIG. 9 is an image obtained by observing with an optical microscope aportion of a lengthwise end portion of a solid electrolytic capacitoraccording to the embodiment.

FIG. 10 shows images of solid electrolytic capacitors according toExamples 18-22 at first and second end surfaces each in a front view.

FIG. 11 shows images of solid electrolytic capacitors according tocomparative examples 9-13 at first and second end surfaces each in afront view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will now be described hereinafterin detail with reference to the drawings. In the following embodiment,identical or common components are identically denoted in the figuresand will not be described repeatedly. Further, in the figures, Lrepresents a lengthwise direction of a later-described insulating resinbody and corresponding to a first direction, T represents a heightwisedirection of the insulating resin body and corresponding to a seconddirection, and W represents a widthwise direction of the insulatingresin body and corresponding to a third direction. The second directionis orthogonal to the first direction, and the third direction isorthogonal to the first direction and the second direction.

FIG. 1 is a perspective view of a solid electrolytic capacitor accordingto an embodiment. FIG. 2 is a cross-sectional view of the solidelectrolytic capacitor taken along a line II-II shown in FIG. 1. FIG. 3is an enlarged cross-sectional view of a portion III shown in FIG. 2.FIG. 4 is a cross-sectional view of the solid electrolytic capacitortaken along a line IV-IV shown in FIG. 2. With reference to FIG. 1 toFIG. 4, a solid electrolytic capacitor 100 according to the embodimentwill be described.

As shown in FIG. 1 to FIG. 4, solid electrolytic capacitor 100 accordingto the embodiment has a generally rectangular parallelepiped externalshape. Solid electrolytic capacitor 100 has external dimensions forexample of 3.5 mm in lengthwise direction L, 2.8 mm in widthwisedirection W, and 1.9 mm in heightwise direction T.

Solid electrolytic capacitor 100 includes a plurality of capacitorelements 170, a leading conductor layer 180, an insulating resin body110, a first external electrode 120, and a second external electrode130. While in the embodiment shown, solid electrolytic capacitor 100includes a plurality of capacitor elements 170, the present invention isnot limited thereto, and solid electrolytic capacitor 100 may include atleast one capacitor element 170.

In insulating resin body 110, the plurality of capacitor elements 170and leading conductor layer 180 are buried. Insulating resin body 110has a generally rectangular parallelepiped external shape. Insulatingresin body 110 has a first main surface 110 a and a second main surface110 b opposite to each other in heightwise direction T, a first sidesurface 110 c and a second side surface 110 d opposite to each other inwidthwise direction W, and a first end surface 110 e and a second endsurface 110 f opposite to each other in lengthwise direction L.

Insulating resin body 110 has a generally rectangular parallelepipedexternal shape, as described above, with corners and ridges thereofrounded. A corner is a portion where three surfaces of insulating resinbody 110 meet one another, and a ridge is a portion where two surfacesof insulating resin body 110 meet each other. The shape of insulatingresin body 110 will more specifically be described later with referenceto FIGS. 5 to 7.

At least one of first main surface 110 a, second main surface 110 b,first side surface 110 c, second side surface 110 d, first end surface110 e, and second end surface 110 f may have a recess and a projection.

Insulating resin body 110 is composed of a substrate 111 serving as asecond insulating resin portion, and a mold portion 112 serving as afirst insulating resin portion provided on substrate 111.

Substrate 111 is, for example, a glass epoxy substrate, and is made of acomposite material such as FRP (Fiber Reinforced Plastics). A surface ofsubstrate 111 facing outward defines second main surface 110 b ofinsulating resin body 110. As a material constituting substrate 111, acomposite material containing a woven fabric or a nonwoven fabriccomposed of carbon, glass, silica or the like in an insulating resinsuch as an epoxy resin can be used. Substrate 111 is, for example, 100μm in thickness.

Mold portion 112 is made of an insulating resin such as epoxy resin inwhich glass or an oxide of Si is dispersed and mixed as a filler. Moldportion 112 is provided on substrate 111 so as to cover the plurality ofcapacitor elements 170 and leading conductor layer 180. A surface ofmold portion 112 located on a side opposite to a side on which substrate111 is located defines first main surface 110 a of insulating resin body110.

A plurality of conductive particles are present in each of first endsurface 110 e and second end surface 110 f of insulating resin body 110.The conductive particles contain Pd. When forming a first externalelectrode 120 and a second external electrode 130, which will bedescribed later, the conductive particles act as a catalytic metalserving as a core for plating. First end surface 110 e and second endsurface 110 f of insulating resin body 110 preferably have a surfaceroughness (Ra) of 2.2 μm or more and 8.3 μm or less.

The plurality of capacitor elements 170 each include an anode portion140, a dielectric layer 150, and a cathode portion 160. Anode portion140 is composed of a metal layer 141 extending in lengthwise directionL. In the embodiment, anode portion 140 includes a first plating film142 and a second plating film 143 provided at metal layer 141.

Metal layer 141 has an external surface provided with a plurality ofrecesses. The external surface of metal layer 141 is porous. Since theexternal surface of metal layer 141 is porous, metal layer 141 has anincreased surface area. Note that metal layer 141 is not limited tohaving both a front surface and a back surface porously, and instead mayhave only one of the front surface and the back surface porously. Forexample, only the back surface of metal layer 141 on a side facingsecond main surface 110 b of insulating resin body 110 may be porous.

Metal layer 141 contains Al. Metal layer 141 is made of, for example, analuminum foil having a porous external surface.

An end surface of metal layer 141 closer to second end surface 110 f iscovered with first plating film 142. First plating film 142 is coveredwith second plating film 143. First plating film 142 contains Zn. Secondplating film 143 contains Ni. Note that first plating film 142 andsecond plating film 143 may be dispensed with.

Dielectric layer 150 is provided on an external surface of metal layer141. Dielectric layer 150 is composed for example of an oxide of Al.Specifically, dielectric layer 150 is made of an oxide of Al formed byoxidizing an external surface of metal layer 141.

Cathode portion 160 has a solid electrolyte layer 161 and a currentcollector layer. Solid electrolyte layer 161 is provided on a portion ofan external surface of dielectric layer 150. Solid electrolyte layer 161is not provided on an external surface of dielectric layer 150 locatedon a side opposite to that of cathode portion 160 and provided on anexternal surface of metal layer 141 closer to second end surface 110 f.The external surface of dielectric layer 150 of this portion is coveredwith an insulating resin layer 151 described later.

As shown in FIG. 3, solid electrolyte layer 161 is provided to fill theplurality of recesses of metal layer 141. Note, however, that solidelectrolyte layer 161 covering the above described portion of theexternal surface of dielectric layer 150 suffices, and metal layer 141may have a recess which is not filled with solid electrolyte layer 161.Solid electrolyte layer 161 is made of a polymer containing a conductivepolymer such as poly (3,4-ethylenedioxythiophene), for example.

The current collector layer is provided on an external surface of solidelectrolyte layer 161. The current collector layer is composed of afirst current collector layer 162 provided on an external surface ofsolid electrolyte layer 161 and a second current collector layer 163provided on an external surface of first current collector layer 162.First current collector layer 162 contains C. Second current collectorlayer 163 contains Ag.

Note that the current collector layer may not include second currentcollector layer 163. When the current collector layer includes secondcurrent collector layer 163, second current collector layer 163 mayinclude at least one type of metal other than Ag, such as Al, Cu and Ni,and Ag. Alternatively, the current collector layer may be composed offirst current collector layer 162, second current collector layer 163,and a third current collector layer provided on an external surface ofsecond current collector layer 163. In that case, second currentcollector layer 163 and the third current collector layer each includeat least one type of metal other than Ag, such as Al, Cu and Ni, and Ag.

Of the layers constituting the current collector layer, a layer otherthan first current collector layer 162 at least is composed of a pastecontaining the above metals. As a base material composing the paste,thermosetting resin, thermoplastic resin, elastomer or the like can beused. As the thermosetting resin, epoxy resin, polyimide resin or thelike can be used. As the thermoplastic resin, acrylic resin,polyethylene resin, polypropylene resin, Teflon (registered trademark)resin or the like can be used. As the elastomer, a material havingrubbery elasticity such as natural rubber, synthetic rubber, siliconrubber, fluorine rubber, polyurethane resin, polyester resin or the likecan be used. The above base material may be a mixture of a plurality oftypes of materials. First current collector layer 162 may be composed ofthe above paste containing C or may be composed of graphite.

When each layer composing the current collector layer is composed of apaste with thermoplastic resin or elastomer serving as a base material,an impact, mechanical stress, and stress caused by a difference incoefficient of thermal expansion between materials, that act in aproduction process and at a time of formation before mold portion 112 isformed, can be relieved and dielectric layer 150 can be prevented fromcracking, and thus an increase of a leakage current of the solidelectrolytic capacitor can be prevented.

When a case in which each layer composing the current collector layer iscomposed of a paste with thermosetting resin serving as a base materialis compared with a case in which each layer composing the currentcollector layer is composed of a paste with thermoplastic resin orelastomer serving as a base material, the former tends to provide asolid electrolytic capacitor providing a larger leakage current than thelatter, however, the former can suppress deterioration in ESR of thesolid electrolytic capacitor attributed to its thermal hysteresis. Forexample, when first current collector layer 162 may be composed of apaste with thermoplastic resin or elastomer serving as a base material,and second current collector layer 163 may be composed of a paste withthermosetting resin serving as a base material. Which base material foreach layer composing the current collector layer is combined withanother can be selected as appropriate.

As has been described above, an external surface of dielectric layer 150located on a side opposite to that of cathode portion 160 and free ofsolid electrolyte layer 161, and provided on an external surface ofmetal layer 141 closer to second end surface 110 f, is covered withinsulating resin layer 151.

As shown in FIG. 3, insulating resin layer 151 is provided so as to filla plurality of recess portions of an external surface of metal layer 141closer to second end surface 110 f. Insulating resin layer 151 containsan insulating resin such as polyimide resin or polyamide imide resin.

A length of insulating resin layer 151 in lengthwise direction L ispreferably equal to or greater than a length of insulating resin body110 in lengthwise direction L multiplied by 0.025 and equal to or lessthan the length of insulating resin body 110 in lengthwise direction Lmultiplied by 0.5. This can maintain an electrostatic capacity of solidelectrolytic capacitor 100 and reduce ESR thereof while ensuringreliability thereof.

When the length of insulating resin layer 151 is smaller than the lengthof insulating resin body 110 multiplied by 0.025, then, in a productionprocess described later (at step S10) when an end surface of metal layer141 exposed at an end surface of a chip is plated with a platingsolution the plating solution may penetrate into insulating resin body110 along an external surface of dielectric layer 150 and cause a shortcircuit. In contrast, when the length of insulating resin layer 151 islarger than the length of insulating resin body 110 multiplied by 0.5,the solid electrolytic capacitor may have a reduced electrostaticcapacity and also have an increased ESR.

Insulating resin layer 151 is preferably 5 μm or more and 30 μm or lessin thickness. This can maintain an electrostatic capacity of solidelectrolytic capacitor 100 and reduce ESR thereof while ensuringreliability thereof.

When the thickness of insulating resin layer 151 is smaller than 5 μm,then, in the production process described later (at step S10) when theend surface of metal layer 141 exposed at the end surface of the chip isplated with a plating solution the plating solution may not beeffectively prevented from penetrating into insulating resin body 110along an external surface of dielectric layer 150. In contrast, when thethickness of insulating resin layer 151 is larger than 30 μm, then, instacking a plurality of capacitor elements, adjacent capacitor elementshave their current collector layers connected unstably, and the solidelectrolytic capacitor may be impaired in reliability.

As shown in FIG. 2, the plurality of capacitor elements 170 are stackedin heightwise direction T. Mutually adjacent capacitor elements 170 havetheir respective current collector layers connected to each other by aconnecting conductor layer 190. A width of connecting conductor layer190 in widthwise direction W is equivalent to a width of metal layer 141in widthwise direction W. Connecting conductor layer 190 contains Ag.

Leading conductor layer 180 is provided on substrate 111, which is aportion of insulating resin body 110. Leading conductor layer 180 ispositioned inside insulating resin body 110 closer to second mainsurface 110 b.

A width of leading conductor layer 180 in widthwise direction W isequivalent to a width of metal layer 141 in widthwise direction W. Alength of leading conductor layer 180 in lengthwise direction L ispreferably equal to or greater than the length of insulating resin body110 in lengthwise direction L multiplied by 0.3 and equal to or lessthan the length of insulating resin body 110 in lengthwise direction Lmultiplied by 0.8. This can reduce the solid electrolytic capacitor'sESR while ensuring that the solid electrolytic capacitor is reliable.

When a length of leading conductor layer 180 in lengthwise direction Lis less than the length of insulating resin body 110 in lengthwisedirection L multiplied by 0.3, the solid electrolytic capacitor wouldhave an ESR higher than 30 mΩ. In contrast, when the length of leadingconductor layer 180 in lengthwise direction L is larger than the lengthof insulating resin body 110 in lengthwise direction L multiplied by0.8, a short circuit may be caused between leading conductor layer 180and second external electrode 130, and the solid electrolytic capacitoris impaired in reliability.

Leading conductor layer 180 is preferably 10 μm or more and 100 μm orless in thickness. This can reduce solid electrolytic capacitor 100'sESR while miniaturizing solid electrolytic capacitor 100. When thethickness of leading conductor layer 180 is less than 10 μm, the solidelectrolytic capacitor has an ESR higher than 30 mΩ. When the thicknessof leading conductor layer 180 is larger than 100 μm, the solidelectrolytic capacitor is prevented from being miniaturized.

The distance in lengthwise direction L between a position closest tofirst end surface 110 e at a portion where leading conductor layer 180and connecting conductor layer 190 are connected together and first endsurface 110 e is preferably 87.5 μm or more and 1750 μm or less. Thiscan minimize solid electrolytic capacitor 100 while ensuring that thesolid electrolytic capacitor is reliable.

When the above distance is less than 87.5 μm, then, in the productionprocess described later (at step S10) when the plating solution used toplate an end surface of metal layer 141 penetrates along an externalsurface of leading conductor layer 180, the plating solution may reach acapacitor element, and impair the solid electrolytic capacitor inreliability. When the above distance is larger than 1750 μm, the solidelectrolytic capacitor is prevented from being miniaturized.

Leading conductor layer 180 contains Cu. In the embodiment, an endsurface of leading conductor layer 180 closer to first end surface 110 eis covered with a third plating film 181. Third plating film 181contains Ni. Note that third plating film 181 may be dispensed with.

Leading conductor layer 180 is connected to the current collector layerof one of the plurality of capacitor elements 170. Specifically, amongthe plurality of capacitor elements 170, a capacitor element 170positioned on the side of one end closer to second main surface 110 b inheightwise direction T is adjacent to leading conductor layer 180. Thecurrent collector layer of only capacitor element 170 adjacent toleading conductor layer 180 is connected to leading conductor layer 180by connecting conductor layer 190.

First external electrode 120 extends from first end surface 110 e ofinsulating resin body 110 to first main surface 110 a, second mainsurface 110 b, first side surface 110 c, and second side surface 110 dthereof. First external electrode 120 is electrically connected tocathode portion 160 of each of the plurality of capacitor elements 170via leading conductor layer 180.

First external electrode 120 is composed of at least one plating layerprovided on first end surface 110 e of insulating resin body 110.Specifically, first external electrode 120 is composed of a firstplating layer 121 provided on first end surface 110 e of insulatingresin body 110, a second plating layer 122 provided on first platinglayer 121, and a third plating layer 123 provided on second platinglayer 122. First plating layer 121 contains Cu. Second plating layer 122contains Ni. Third plating layer 123 contains Sn.

First external electrode 120 is directly or indirectly connected toleading conductor layer 180 at first end surface 110 e of insulatingresin body 110. In the present embodiment, first external electrode 120is connected to leading conductor layer 180 with third plating film 181interposed therebetween. That is, third plating film 181 is providedbetween first external electrode 120 and leading conductor layer 180.

Second external electrode 130 extends from second end surface 110 f ofinsulating resin body 110 to first main surface 110 a, second mainsurface 110 b, first side surface 110 c, and second side surface 110 d.Second external electrode 130 is electrically connected to anode portion140 of each of the plurality of capacitor elements 170.

Second external electrode 130 is composed of at least one plating layerprovided on second end surface 110 f of insulating resin body 110.Specifically, second external electrode 130 is composed of a firstplating layer 131 provided on second end surface 110 f of insulatingresin body 110, a second plating layer 132 provided on first platinglayer 131, and a third plating layer 133 provided on second platinglayer 132. First plating layer 131 contains Cu. Second plating layer 132contains Ni. Third plating layer 133 contains Sn.

Second external electrode 130 is directly or indirectly connected tometal layer 141 of each of the plurality of capacitor elements 170 atsecond end surface 110 f of insulating resin body 110. Second externalelectrode 130 is connected to metal layer 141 of each of the pluralityof capacitor elements 170 with first plating film 142 and second platingfilm 143 interposed therebetween. That is, first plating film 142 andsecond plating film 143 are provided between metal layer 141 of each ofthe plurality of capacitor elements 170 and second external electrode130.

FIG. 5 is a front view of a first end surface of a solid electrolyticcapacitor according to the embodiment. FIG. 6 is a front view of asecond end surface of the solid electrolytic capacitor according to theembodiment. FIG. 7 is a bottom view of the solid electrolytic capacitoraccording to the embodiment. Note that in FIG. 7 leading conductor layer180 is indicated by a broken line. A shape of insulating resin body 110included in solid electrolytic capacitor 100 will be described withreference to FIGS. 5 to 7.

As shown in FIGS. 5 to 7, insulating resin body 110 includes a firstconnecting portion 1101 connecting first end surface 110 e and firstmain surface 110 a, a second connecting portion 1102 connecting firstend surface 110 e and second main surface 110 b, a third connectingportion 1103 connecting second end surface 110 f and first main surface110 a, and a fourth connecting portion 1104 connecting second endsurface 110 f and second main surface 110 b.

Insulating resin body 110 includes a fifth connecting portion 1105connecting first end surface 110 e and first side surface 110 c, a sixthconnecting portion 1106 connecting first end surface 110 e and secondside surface 110 d, a seventh connecting portion 1107 connecting secondend surface 110 f and first side surface 110 c, and an eighth connectingportion 1108 connecting second end surface 110 f and second side surface110 d.

First connecting portion 1101 and third connecting portion 1103 areprovided at mold portion 112. Second connecting portion 1102 and fourthconnecting portion 1104 are provided at substrate 111.

First connecting portion 1101, second connecting portion 1102, thirdconnecting portion 1103, and fourth connecting portion 1104 each have afirst chamfered portion. Preferably, the first chamfered portion extendsfrom the side of first side surface 110 c to the side of second sidesurface 110 d. Note that when first end surface 110 e and first andsecond main surfaces 110 a and 110 b partially meet one another, firstconnecting portion 1101 and second connecting portion 1102 include aridge between first end surface 110 e and first and second main surfaces110 a and 110 b. When second end surface 110 f and first and second mainsurfaces 110 a and 110 b partially meet one another, third connectingportion 1103 and fourth connecting portion 1104 include a ridge betweensecond end surface 110 f and first and second main surfaces 110 a and110 b.

As shown in FIG. 2, first chamfered portion has a curved shape in across-sectional view as seen in widthwise direction W. Morespecifically, the first chamfered portion has a generally arcuate shape.

Herein, as shown in FIG. 2, assuming that the first chamfered portionhas a radius of curvature r, a point on a circle having the radius ofcurvature r with a center of curvature O has coordinates represented as(x, y), and the center of curvature O has coordinates of (a, b), acircle having the radius of curvature r with the center of curvature Ocan be expressed by the following expression (1):(x−a)²+(y−b)² =r ²  Expression (1).

By substituting each of the coordinates of arbitrary three points on thecircle at first connecting portion 1101 (for example, points A, B and Cshown in FIG. 2) into the above expression (1), and solving these as asimultaneous equation, the radius of curvature r and the coordinates (a,b) of the center of curvature can be calculated.

Note that the coordinates of points A, B and C can be measured asfollows: insulating resin body 110 is polished to a position of about ½of a dimension thereof in widthwise direction W to expose a crosssection along lengthwise direction L and heightwise direction T, and thecross section is imaged using a scanning electron microscope (SEM) orthe like. It is preferable to set an average value of radii of curvatureobtained from five capacitor elements as the radius of curvature r ofsolid electrolytic capacitor 100.

Substrate 111 serving as the second insulating resin portion is harderthan mold portion 112 serving as the first insulating resin portion, andthe first chamfered portions of first connecting portion 1101 and thirdconnecting portion 1103 are rounder than the first chamfered portions ofsecond connecting portion 1102 and fourth connecting portion 1104. Morespecifically, the first chamfered portion at first connecting portion1101 and third connecting portion 1103 has a radius of curvature largerthan that of the first chamfered portion at second connecting portion1102 and fourth connecting portion 1104.

Note that while a case has been described by way of example in which dueto a difference in hardness between mold portion 112 and substrate 111the first chamfered portion at first connecting portion 1101 and thirdconnecting portion 1103 has a radius of curvature larger than that ofthe first chamfered portion at second connecting portion 1102 and fourthconnecting portion 1104, this is not exclusive, and regardless of adifference in hardness, the first chamfered portion may have a radius ofcurvature larger than that of the first chamfered portion at secondconnecting portion 1102 and fourth connecting portion 1104. For example,even when insulating resin body 110 is composed only of the moldportion, the first chamfered portion may have a radius of curvaturelarger than that of the first chamfered portion at second connectingportion 1102 and fourth connecting portion 1104.

Note that the first chamfered portion when seen in widthwise direction Wis not limited to a curved shape and may instead be a bent shape. Inthat case, when seen in widthwise direction W, a cross section alonglengthwise direction L and heightwise direction T has a polygonal shapein which each interior angle is 90 degrees or more.

Furthermore, fifth connecting portion 1105, sixth connecting portion1106, seventh connecting portion 1107, and eighth connecting portion1108 each have a second chamfered portion. The second chamfered portionhas a curved shape in a cross-sectional view as seen in heightwisedirection T, as shown in FIG. 4. More specifically, the second chamferedportion has a generally arcuate shape.

The radius of curvature of the second chamfered portion can also bemeasured by the same method as the radius of curvature of the firstchamfered portion is measured. In that case, for the measurement,insulating resin body 110 is polished to a position of about ½ of adimension thereof in heightwise direction T to expose a cross sectionalong lengthwise direction L and widthwise direction W.

The second chamfered portion when seen in heightwise direction T is notlimited to a curved shape and may instead be a bent shape. In this case,when seen in the second direction, a cross section along lengthwisedirection L and widthwise direction W has a polygonal shape in whicheach interior angle is 90 degrees or more.

First external electrode 120 extends from first end surface 110 e acrossfirst connecting portion 1101, second connecting portion 1102, fifthconnecting portion 1105, and sixth connecting portion 1106 to first andsecond main surfaces 110 a and 110 b and first and second side surfaces110 c and 110 d. That is, first external electrode 120 is disposed alongthe first chamfered portion provided at first connecting portion 1101and second connecting portion 1102, and the second chamfered portionprovided at fifth connecting portion 1105 and sixth connecting portion1106.

As first external electrode 120 is along the first chamfered portion andthe second chamfered portion, a stress acting on first externalelectrode 120 at a boundary between first end surface 110 e and firstand second main surfaces 110 a and 110 b can be relieved, and adhesionof first external electrode 120 to a surface of insulating resin body110 on the side of first end surface 110 e can be improved. This canincrease adhesion strength of first external electrode 120 and suppresspeeling of first external electrode 120 off insulating resin body 110 atthe time of formation or after production. As a result, solidelectrolytic capacitor 100 can be improved in reliability.

Second external electrode 130 extends from second end surface 110 facross third connecting portion 1103, fourth connecting portion 1104,seventh connecting portion 1107, and eighth connecting portion 1108 tofirst and second main surfaces 110 a and 110 b and first and second sidesurfaces 110 c and 110 d. That is, second external electrode 130 isdisposed along the first chamfered portion provided at third connectingportion 1103 and fourth connecting portion 1104, and the secondchamfered portion provided at seventh connecting portion 1107 and eighthconnecting portion 1108.

As second external electrode 130 is along the first chamfered portionand the second chamfered portion, a stress acting on second externalelectrode 130 at a boundary between second end surface 110 f and firstand second main surfaces 110 a and 110 b can be relieved, and adhesionof second external electrode 130 to a surface of insulating resin body110 on the side of second end surface 110 f can be improved. This canincrease adhesion strength of second external electrode 130 and suppresspeeling of second external electrode 130 off insulating resin body 110at the time of formation or after production. As a result, solidelectrolytic capacitor 100 can be improved in reliability.

Furthermore, first end surface 110 e and second end surface 110 f ofinsulating resin body 110 preferably have a surface roughness (Ra) of2.2 μm or more and 8.3 μm or less. This can improve overall adhesion offirst external electrode 120 and second external electrode 130 to firstend surface 110 e and second end surface 110 f.

First end surface 110 e and second end surface 110 f of insulating resinbody 110 each have a rough surface and have fine recesses andprojections. First plating layers 121 and 131 containing Cu are eachformed so as to enter these fine recesses and projections and theiradhesion to insulating resin body 110 is enhanced by an anchor effect.This can also suppress peeling of first and second external electrodes120 and 130 off insulating resin body 110.

When solid electrolytic capacitor 100 is mounted on a mounting substrateby using a bonding member such as solder, a tensile force from thebonding member acts more on the side of the main surface of theinsulating resin body located farther from the mounting substrate thanon the side of the main surface of the insulating resin body locatedcloser to the mounting substrate.

Here, as has been described above, with the first chamfered portions atfirst connecting portion 1101 and third connecting portion 1103 beingrounder than the first chamfered portions at second connecting portion1102 and fourth connecting portion 1104 located closer to substrate 111,when the substrate 111 side is mounted on the mounting substrate, thefirst chamfered portions at first connecting portion 1101 and thirdconnecting portion 1103 that are rounder can significantly alleviate thetensile force exerted from the bonding member. This can suppresscracking caused by reflow or the like, and ensure mountability andelectrical characteristics at the time of mounting. As a result, solidelectrolytic capacitor 100 can be improved in reliability.

(Method of Producing Solid Electrolytic Capacitor)

FIG. 8 is a flowchart of producing a solid electrolytic capacitoraccording to the embodiment. A method of producing solid electrolyticcapacitor 100 according to the embodiment will be described withreference to FIG. 8.

As shown in FIG. 8, in producing solid electrolytic capacitor 100according to an embodiment of the present invention, initially,dielectric layer 150 is provided on an external surface of metal layer141 (step S1). In the present embodiment, an aluminum foil serving asmetal layer 141 is immersed in an aqueous solution of ammonium adipateand oxidized to produce an oxide of Al to serve as dielectric layer 150.Note than when an aluminum foil in which an oxide of Al has already beenformed is cut and used as metal layer 141, then, in order to form anoxide of Al on the cut surface, metal layer 141 having been cut is againimmersed in an aqueous solution of ammonium adipate and oxidized.

Subsequently, a portion of metal layer 141 is masked (step S2). Thismasking is performed to define a region in which solid electrolyte layer161 is formed in a subsequent step. Specifically, a masking agent madeof an insulating resin such as polyimide resin or polyamide-imide resinis applied to a portion of an external surface of metal layer 141. Aportion of a masking portion formed in this step serves as insulatingresin layer 151.

Subsequently, solid electrolyte layer 161 is provided on a portion of anexternal surface of dielectric layer 150 (step S3). More specifically,solid electrolyte layer 161 is formed by adhering a solid electrolytedispersion solution to an external surface of dielectric layer 150located in the region in which solid electrolyte layer 161 is formed asdefined by the masking portion formed in step S2.

Subsequently, a current collector layer is provided on an externalsurface of solid electrolyte layer 161 (step S4). Specifically, firstcurrent collector layer 162 is formed by applying C to an externalsurface of solid electrolyte layer 161. Second current collector layer163 is formed by applying Ag to an external surface of first currentcollector layer 162.

Second current collector layer 163 may not be formed. Second currentcollector layer 163 may include at least one type of metal other thanAg, such as Al, Cu and Ni, and Ag. Alternatively, a third currentcollector layer may be further formed on an external surface of secondcurrent collector layer 163. In that case, second current collectorlayer 163 and the third current collector layer each include at leastone type of metal other than Ag, such as Al, Cu and Ni, and Ag.

When each layer composing the current collector layer is composed of apaste containing the above metals, each layer is formed by applying thepaste. When the paste includes a base material of thermosetting resin orthermosetting elastomer, then, after the paste is applied, the paste isheated and thus thermally set. When first current collector layer 162 iscomposed of graphite, first current collector layer 162 is formed byapplying graphite.

Subsequently, capacitor element 170 is stacked on substrate 111 providedwith leading conductor layer 180 (step S5). Specifically, the currentcollector layer of capacitor element 170 and leading conductor layer 180are connected by a conductive adhesive such as an Ag paste, and thecurrent collector layers of mutually adjacent capacitor elements 170 areconnected.

Subsequently, substrate 111 and capacitor element 170 arethermocompression-bonded (step S6). The conductive adhesive are heatedand cured and thus becomes connecting conductor layer 190.

Subsequently, substrate 111 and capacitor element 170thermocompression-bonded together are molded with an insulating resin(step S7). More specifically, a molding method is employed: substrate111 is attached on an upper half die, and in a condition in which aninsulating resin such as epoxy resin in which glass or an oxide of Si isdispersed and mixed as a filler is heated and melted in a cavity of alower half die, the upper and lower half dies are clamped together andthe insulating resin is solidified to form mold portion 112.

Subsequently, substrate 111 and capacitor element 170 are cut so as todivide the masking portion formed in step S2 (step S8). Specifically,substrate 111 and capacitor element 170 in a molded state are cut bypressing, dicing or laser cutting. Through this step, a chip includinginsulating resin body 110 is formed.

Subsequently, the chip is barreled (step S9). Specifically, the chip isenclosed together with a polishing material in a small box called abarrel, and the chip is polished by rotating the barrel. As a result,the chip has corners and ridges rounded.

More specifically, by barreling, first connecting portion 1101connecting first end surface 110 e and first main surface 110 atogether, second connecting portion 1102 connecting first end surface110 e and second main surface 110 b together, third connecting portion1103 connecting second end surface 110 f and first main surface 110 atogether, and a fourth connecting portion 1104 connecting second endsurface 110 f and second main surface 110 b together are provided withthe above described first chamfered portion. Furthermore, fifthconnecting portion 1105 connecting first end surface 110 e and firstside surface 110 c, sixth connecting portion 1106 connecting first endsurface 110 e and second side surface 110 d, seventh connecting portion1107 connecting second end surface 110 f and first side surface 110 c,and eighth connecting portion 1108 connecting second end surface 110 fand second side surface 110 d are provided with the above describedsecond chamfered portion.

Subsequently, an end surface of metal layer 141 exposed at an endsurface of the chip is plated (step S10). Specifically, the chip's oilcontent is removed with an alkali treatment agent. Alkali etching isperformed to remove an oxide film on an end surface of metal layer 141.By a smut removing step, a smut on an end surface of metal layer 141 isremoved. Zn is displaced and deposited by a zincate treatment to formfirst plating film 142 on an end surface of metal layer 141. By anelectroless Ni plating treatment, second plating film 143 is formed onfirst plating film 142. In doing so, third plating film 181 is formed onan end surface of leading conductor layer 180.

Subsequently, a conductance imparting liquid is adhered to opposite endsof the chip (step S11). Specifically, a portion of the chip other thanthe opposite ends is masked. The chip is degreased with a surfactant inorder to improve the conductance imparting liquid's wettability withrespect to the surfaces of the opposite ends of the chip and alsofacilitate the conductive particles contained in the conductanceimparting liquid to be adsorbed in the opposite ends of the chip. As aconditioner also having a degreasing power, a surfactant of any one ofanion, cation, amphoteric ion and non-ion is selected and used dependingon the type of the conductance imparting liquid.

Note that while the conductive particles contained in the conductanceimparting liquid include Pd as a catalyst metal serving as a core ofplating, this is not exclusive and they may contain at least one type ofmetal selected from the group consisting of Pd, Sn, Ag, and Cu. Theconductance imparting liquid is a solution containing ions of the abovemetal or a colloidal solution of the above metal.

The chip having opposite ends with the conductance imparting liquidadhering thereto is washed with water or a solvent and then dried toform a conductive film on the opposite ends of the chip. Thus aplurality of conductive particles are present in each of first endsurface 110 e and second end surface 110 f of insulating resin body 110.

Subsequently, the chip has the opposite ends plated to form firstexternal electrode 120 and second external electrode 130 (step S12).Specifically, using a plating barrel apparatus, first plating layers 121and 131 containing Cu are formed on the conductive films of the oppositeends of the chip by electrolytic plating. First plating layer 121 andfirst plating layer 131 are formed such that conductive particlesadhering to the opposite ends the chip are used as a core.

First plating layer 121 extends from first end surface 110 e along thefirst and second chamfered portions to reach first and second mainsurfaces 110 a and 110 b and first and second side surfaces 110 c and110 d.

First plating layer 131 extends from second end surface 110 f along thefirst and second chamfered portions to reach first and second mainsurfaces 110 a and 110 b and first and second side surfaces 110 c and110 d.

Subsequently, similarly, by electrolytic plating, second plating layer122 containing Ni is formed on first plating layer 121 and secondplating layer 132 containing Ni is formed on first plating layer 131.Subsequently, similarly, by electrolytic plating, third plating layer123 containing Sn is formed on second plating layer 122 and thirdplating layer 133 containing Sn is formed on second plating layer 132.

Subsequently, the chip is marked (step S13). Specifically, a mark formaking first external electrode 120 and second external electrode 130identifiable is marked on first main surface 110 a or second mainsurface 110 b of insulating resin body 110 with a laser marker or thelike.

Again, as shown in FIG. 7, in solid electrolytic capacitor 100 accordingto the embodiment, leading conductor layer 180 is visible wheninsulating resin body 110 is seen on the side of second main surface 110b. Thus, in the process for producing solid electrolytic capacitor 100,after first external electrode 120 and second external electrode 130 areformed in step S12, then, in step S13, by observing insulating resinbody 110 on the second main surface 110 b side, first external electrode120 and second external electrode 130 can be identified by confirmingthe arrangement of leading conductor layer 180. Based on the identifiedresult, the mark for making first external electrode 120 and secondexternal electrode 130 identifiable can be marked on first main surface110 a or second main surface 110 b of insulating resin body 110.

If leading conductor layer 180 is invisible with insulating resin body110 seen on the second main surface 110 b side, the marking must be donein a state in which insulating resin body 110 has first end surface 110e and second end surface 110 f exposed, i.e., before first externalelectrode 120 and second external electrode 130 are formed. When themarking is done before first external electrode 120 and second externalelectrode 130 are formed, the mark will be erased by microetchingperformed in step S11, and first external electrode 120 and secondexternal electrode 130 cannot be identified. Accordingly, in that case,it is necessary to perform marking which is not erased by microetching,which increases a restriction on a condition for producing the solidelectrolytic capacitor.

In solid electrolytic capacitor 100 according to the present embodiment,when insulating resin body 110 is seen on the second main surface 110 bside, leading conductor layer 180 is visible, and a degree of freedom ofa condition for producing the solid electrolytic capacitor can beincreased.

Through the series of the steps described above, solid electrolyticcapacitor 100 can be produced. It should be noted that step S13 is notnecessarily performed.

Solid electrolytic capacitor 100 according to the present embodiment hasfirst external electrode 120 and second external electrode 130 eachcomposed of a plating layer and accordingly does not require routing ananode terminal and a cathode terminal outside resin, as done for a solidelectrolytic capacitor described in International Publication No.2013/088954. As a result, solid electrolytic capacitor 100 can beminiaturized while it has ESR and ESL reduced. In addition, solidelectrolytic capacitor 100 can have an electrostatic capacity increasedper unit volume.

Furthermore, solid electrolytic capacitor 100 according to the presentembodiment is such that second external electrode 130 is connected tometal layer 141 at second end surface 110 f and An external surface ofdielectric layer 150 located on a side opposite to that of cathodeportion 160 and free of solid electrolyte layer 161, and provided on anexternal surface of metal layer 141 closer to second end surface 110 f,is covered with insulating resin layer 151, and accordingly, solidelectrolytic capacitor 100 according to the present embodiment does notrequire routing an anode terminal outside resin, as done for the solidelectrolytic capacitor described in International Publication No.2013/088954. As a result, solid electrolytic capacitor 100 can beminiaturized while maintaining reliability.

Furthermore, since each of first external electrode 120 and secondexternal electrode 130 has a Ni plating layer and a Sn plating layer,solid electrolytic capacitor 100 is improved in mountability.Specifically, the Ni plating layer has a function to prevent a Cuplating layer from being eroded by solder when mounting solidelectrolytic capacitor 100. The Sn plating layer has a function toimprove wettability with solder when mounting solid electrolyticcapacitor 100, and facilitate mounting solid electrolytic capacitor 100.

In solid electrolytic capacitor 100 according to the present embodiment,insulating resin body 110 has first end surface 110 e and second endsurface 110 f with a surface roughness (Ra) of 2.2 μm or more and 8.3 μmor less, and peeling of first external electrode 120 and second externalelectrode 130 off insulating resin body 110 can be suppressed.

FIG. 9 is an image obtained by observing with an optical microscope aportion of a lengthwise end portion of a solid electrolytic capacitoraccording to the embodiment.

As shown in FIG. 9, first end surface 110 e and second end surface 110 fof insulating resin body 110 each have a rough surface with finerecesses and projections. First plating layers 121 and 131 containing Cuare each formed so as to enter these fine recesses and projections andtheir adhesion to insulating resin body 110 is enhanced by an anchoreffect. As a result, peeling of first and second external electrodes 120and 130 off insulating resin body 110 is suppressed.

Exemplary Experiment 1

Hereinafter, exemplary experiment 1 will be described which investigateda relationship between a surface roughness of an end surface of theinsulating resin body and a rate of occurrence of peeling of an externalelectrode.

The insulating resin body had an end surface with surface roughnesses(Ra) of 8.3 μm in Example 1, 5.1 μm in Example 2, 2.2 μm in Example 3,9.2 μm in Comparative Example 1, 0.4 μm in Comparative Example 2 and 0.1μm in Comparative Example 3. Whether an external electrode formed bybarrel plating peeled or not was investigated. 100 samples were preparedfor each of Example 1, Example 2, Comparative Example 1 and ComparativeExample 2. The surface roughness (Ra) of the end surface of theinsulating resin body is determined by removing an external electrodewith a stripping agent such as an en strip or a mel strip to expose anend surface of the insulating resin body, and measuring the surfaceroughness (Ra) using a laser microscope at a position of a centerportion in widthwise direction W and a center portion in heightwisedirection T.

TABLE 1 surface roughness (Ra) of end surface of rate of occurrence ofinsulating resin body peeling of external (Ra) electrode (%) comparativeexample 1 9.2 10 example 1 8.3 0 example 2 5.1 1 example 3 2.2 3comparative example 2 0.4 26 comparative example 3 0.1 41

Table 1 is a table showing a result of exemplary experiment 1. As shownin Table 1, in Example 1, in which the surface roughness (Ra) of the endsurface of the insulating resin body was 8.3 μm, no solid electrolyticcapacitor having the external electrode peeled off was observed. InExample 2, in which the surface roughness (Ra) of the end surface of theinsulating resin body was 5.1 μm, the rate of occurrence of peeling ofthe external electrode was 1%, which was no larger than 5%. In Example3, in which the surface roughness (Ra) of the end surface of theinsulating resin body was 2.2 the rate of occurrence of peeling of theexternal electrode was 3%, which was no larger than 5%.

In contrast, in comparative example 1, in which the surface roughness(Ra) of the end surface of the insulating resin body was 9.2 μm, therate of occurrence of peeling of the external electrode was 10%, whichwas higher than 5%. In comparative example 2, in which the surfaceroughness (Ra) of the end surface of the insulating resin body was 0.4μm, the rate of occurrence of peeling of the external electrode was 26%,which was higher than 5%. In comparative example 3, in which the surfaceroughness (Ra) of the end surface of the insulating resin body was 0.1μm, the rate of occurrence of peeling of the external electrode was 41%,which was higher than 5%.

From the result of exemplary experiment 1, it has been confirmed thatwhen the surface roughness (Ra) of the end surface of the insulatingresin body is 2.2 μm or more and 8.3 μm or less, the rate of occurrenceof peeling of the external electrode can be reduced to 5% or less.

In solid electrolytic capacitor 100 according to the present embodiment,an external surface of dielectric layer 150 located on a side oppositeto that of cathode portion 160 and free of solid electrolyte layer 161,and provided on an external surface of metal layer 141 closer to secondend surface 110 f, is covered with insulating resin layer 151, so thatinsulating resin layer 151 can suppress penetration of a platingsolution plating an end surface of metal layer 141 in step S10 intoinsulating resin body 110 along an external surface of dielectric layer150.

In solid electrolytic capacitor 100 according to the present embodiment,a length of insulating resin layer 151 in lengthwise direction L equalto or greater than the length of insulating resin body 110 in lengthwisedirection L multiplied by 0.025 and equal to or less than the length ofinsulating resin body 110 in lengthwise direction L multiplied by 0.5,allows solid electrolytic capacitor 100 to maintain an electrostaticcapacity and have a reduced ESR while ensuring reliability.

Exemplary Experiment 2

Exemplary experiment 2 will be described which was conducted toinvestigate how the length of the insulating resin layer influences thesolid electrolytic capacitor's electrostatic capacity, ESR andreliability.

A ratio of the length of the insulating resin layer in lengthwisedirection L to the length of the insulating resin body in lengthwisedirection L was 0.025 in Example 4, 0.05 in Example 5, 0.1 in Example 6,0.15 in Example 7, 0.2 in Example 8, 0.25 in Example 9, 0.3 in Example10, 0.35 in Example 11, 0.4 in Example 12, 0.45 in Example 13, 0.5 inExample 14, 0.01 in Comparative Example 4, 0.7 in Comparative Example 5,and 0.9 in Comparative Example 6. Each solid electrolytic capacitor'selectrostatic capacity (μF), ESR (me) and leakage current (μA) weremeasured.

TABLE 2 ratio of length of insulating resin layer to length ofinsulating electrostatic leakage resin body capacity (μF) ESR (mΩ)current (μA) example 4 0.025 33.9 25.8 0.08 example 5 0.05 33.2 25.3 0.1example 6 0.1 33.5 25.6 0.05 example 7 0.15 33.7 24.9 0.01 example 8 0.232.9 25.1 0.02 example 9 0.25 32.9 25.5 0.03 example 10 0.3 32.7 26.70.02 example 11 0.35 32.6 26.8 0.02 example 12 0.4 31.9 26.5 0.03example 13 0.45 31.5 26.9 0.03 example 14 0.5 31.5 27.3 0.03 comparative0.01 33.1 25.6 11560 example 4 comparative 0.7 21.5 60.0 0.03 example 5comparative 0.9 15.5 90.0 0.02 example 6

Table 2 is a table showing a result of exemplary experiment 2. As shownin Table 2, in Examples 4 to 14, in which the length of the insulatingresin layer in lengthwise direction L is equal to or greater than thelength of the insulating resin body in lengthwise direction L multipliedby 0.025 and equal to or less than the length of the insulating resinbody in lengthwise direction L multiplied by 0.5, the solid electrolyticcapacitors had an electrostatic capacity of 30 μF or more, an ESR of 30mΩ or less, and a leakage current of 0.2 μA or less.

In contrast, in Comparative Example 4, in which the length of theinsulating resin layer in lengthwise direction L is less than the lengthof the insulating resin body in lengthwise direction L multiplied by0.05, a significantly high leakage current is observed, and the solidelectrolytic capacitor had low reliability. That is, in step S10 when anend surface of metal layer 141 is plated with a plating solution theplating solution may penetrate into insulating resin body 110 along anexternal surface of dielectric layer 150 and cause a short circuit.

In Comparative Examples 5 and 6, in which the length of the insulatingresin layer in lengthwise direction L is larger than the length of theinsulating resin body in lengthwise direction L multiplied by 0.5, thesolid electrolytic capacitors had an electrostatic capacity less than 30μF and an ESR higher than 30 mΩ.

From the result of exemplary experiment 2, it has been confirmed thatthe length of insulating resin layer 151 in lengthwise direction L beingequal to or greater than the length of insulating resin body 110 inlengthwise direction L multiplied by 0.025 and equal to or less than thelength of insulating resin body 110 in lengthwise direction L multipliedby 0.5 ensures that the solid electrolytic capacitor is reliable whilemaintaining an electrostatic capacity and reducing ESR.

Insulating resin layer 151 having a thickness of 5 μm or more and 30 μmor less ensures that the solid electrolytic capacitor is reliable.

Exemplary Experiment 3

Exemplary experiment 3 will be described which was conducted toinvestigate how the thickness of insulating resin layer 151 influencesthe external appearance of insulating resin body 110 and the solidelectrolytic capacitor's reliability.

The insulating resin layer was 5 μm in Example 15, 15 μm in Example 16,30 μm in Example 17, 2 μm in Comparative Example 7, and 100 μm inComparative Example 8 in thickness. The chip produced in step S8 wasobserved, and when a capacitor element uncovered with the mold portionof the insulating resin body was confirmed, it was determined that theinsulating resin body had a poor appearance. The solid electrolyticcapacitors' leakage currents (μA) were measured.

TABLE 3 Thickness of Appearance of insulating resin insulating resinLeakage current layer (μm) body (μA) example 15 5 good 0.16 example 1615 good 0.09 example 17 30 good 0.05 comparative 2 good 13347 example 7comparative 100 not good 0.07 example 8

Table 3 shows a result of exemplary experiment 3. As shown in Table 3,Examples 15 to 17, in which the insulating resin layer had a thicknessof 5 μm or more and 30 μm or less, provided an insulating resin body ina good appearance and provided a leakage current of 0.2 μA or less.

In contrast, Comparative Example 7, in which the insulating resin layerhad a thickness less than 5 μm, provided an extremely large leakagecurrent and hence a solid electrolytic capacitor having low reliability.That is, when insulating resin layer 151 has a thickness less than 5 μm,insulating resin layer 151 cannot effectively suppress penetration of aplating solution plating an end surface of metal layer 141 in step S10into insulating resin body 110 along an external surface of dielectriclayer 150.

In Comparative Example 8, in which insulating resin layer 151 has athickness larger than 30 μm, the thickness of the stack of the pluralityof capacitor elements is larger than the thickness of the mold portion,and a capacitor element uncovered with the mold portion of theinsulating resin body was confirmed and the insulating resin body thushad a poor external appearance. Furthermore, in that case, when theplurality of capacitor elements are stacked, adjacent capacitor elementshave their current collector layers connected unstably, and the solidelectrolytic capacitor is impaired in reliability.

Note that the length of the insulating resin layer in lengthwisedirection L and the thickness of the insulating resin layer can bemeasured as follows: the insulating resin body is polished to a positionof about ½ of a dimension thereof in widthwise direction W to expose across section along lengthwise direction L and heightwise direction T,and the cross section is imaged using a scanning electron microscope(SEM) or the like. In exemplary experiment 2, the length of theinsulating resin layer in lengthwise direction L was represented by anaverage value of measurement values of five capacitor elements.

In solid electrolytic capacitor 100 according to the present embodiment,a length of leading conductor layer 180 in lengthwise direction L beingequal to or greater than the length of insulating resin body 110 inlengthwise direction L multiplied by 0.3 and equal to or less than thelength of insulating resin body 110 in lengthwise direction L multipliedby 0.8 allows the solid electrolytic capacitor to have a reduced ESRwhile ensuring that the solid electrolytic capacitor is reliable.

When a length of leading conductor layer 180 in lengthwise direction Lis less than the length of insulating resin body 110 in lengthwisedirection L multiplied by 0.3, the solid electrolytic capacitor has anESR higher than 30 mΩ. When a length of leading conductor layer 180 inlengthwise direction L is larger than the length of insulating resinbody 110 in lengthwise direction L multiplied by 0.8, a short circuitmay occur between leading conductor layer 180 and second externalelectrode 130, and the solid electrolytic capacitor is impaired inreliability.

Leading conductor layer 180 having a thickness of 10 μm or more and 100μm or less allows solid electrolytic capacitor 100 to be miniaturizedwhile having a reduced ESR. When the thickness of leading conductorlayer 180 is less than 10 μm, the solid electrolytic capacitor has anESR higher than 30 mΩ. When the thickness of leading conductor layer 180is larger than 100 μm, the solid electrolytic capacitor is preventedfrom being miniaturized.

In solid electrolytic capacitor 100 according to the present embodiment,the distance in lengthwise direction L between a position closest tofirst end surface 110 e at a portion where leading conductor layer 180and connecting conductor layer 190 are connected together and first endsurface 110 e being 87.5 μm or more and 1750 μm or less allows solidelectrolytic capacitor 100 to be miniaturized while ensuring that thesolid electrolytic capacitor is reliable.

When the above distance is less than 87.5 μm, then, in step S10 when aplating solution used to plate an end surface of metal layer 141penetrates along an external surface of leading conductor layer 180 theplating solution may reach a capacitor element, and impair the solidelectrolytic capacitor in reliability. When the above distance is largerthan 1750 μm, the solid electrolytic capacitor is prevented from beingminiaturized.

Note that the length of the leading conductor layer in lengthwisedirection L and the above distance, and the thickness of the leadingconductor layer can be measured as follows: the insulating resin body ispolished to a position of about ½ of a dimension thereof in widthwisedirection W to expose a cross section along lengthwise direction L andheightwise direction T, and the cross section is imaged using a scanningelectron microscope (SEM) or the like.

Exemplary Experiment 4

FIG. 10 shows images of solid electrolytic capacitors according toExamples 18-22 at first and second end surfaces each in a front view.With reference to FIG. 10, the first and second end surfaces of thesolid electrolytic capacitors according to Examples 18 to 22 will bedescribed.

Solid electrolytic capacitors each having a structure similar to that ofthe embodiment produced using a production method in the aboveembodiment were prepared as the solid electrolytic capacitors accordingto Examples 18 to 22. First external electrode 120 on the first endsurface 110 e side and second external electrode 130 on the second endsurface 110 f side of each of the solid electrolytic capacitorsaccording to Examples 18 to 22 were observed with an optical microscope.

In each observation result in FIG. 10, a central bright portion (orwhite portion) is an external electrode located on the first or secondend surface, and a substantially gray portion surrounding the brightportion is a portion of the external electrode located on the first orsecond chamfered portion. It should be noted that the gray portion issurrounded by a black portion serving as a background.

None of the solid electrolytic capacitors according to Examples 18 to 22was observed such that first external electrode 120 and second externalelectrode 130 peeled off the first end surface 110 e side and the secondend surface 110 f side, and they were in a satisfactory state.

Comparative Examples

FIG. 11 shows images of solid electrolytic capacitors according tocomparative examples 9-13 at first and second end surfaces each in afront view. With reference to FIG. 11, the first and second end surfacesof the solid electrolytic capacitors according to comparative examples9-13 will be described.

As the solid electrolytic capacitors according to Comparative Examples 9to 13, solid electrolytic capacitors produced according mutatis mutandisto a production method in the above embodiment were prepared.Specifically, the solid electrolytic capacitor was produced as follows:in the production method according to the embodiment, step S9 ofbarreling a cut chip was omitted, and an external electrode was formedon an end surface side of the chip immediately after it was cut. Inother words, the solid electrolytic capacitors according to ComparativeExamples 9 to 13 do not have the first chamfered portion and the secondchamfered portion.

First external electrode 120 on the first end surface 110 e side andsecond external electrode 130 on the second end surface 110 f side ofeach of the solid electrolytic capacitors according to ComparativeExamples 9 to 13 were observed with an optical microscope.

FIG. 11 shows observation results, which show that a central brightportion (or white portion) is an external electrode provided on thefirst or second end surface. In FIG. 11, as compared with FIG. 9, asubstantially gray portion is not observed around the bright portion,and the first chamfered portion and the second chamfered portion are notformed.

In the solid electrolytic capacitors of Comparative Examples 9 to 11, anexternal electrode was partially peeled around an end surface on eitherthe first end surface's side or the second end surface's side.

In the solid electrolytic capacitor according to Comparative Example 12,first external electrode 120 significantly peeled off on the first endsurface's side, in particular.

In contrast, the solid electrolytic capacitor according to ComparativeExample 13 was not observed such that first external electrode 120 andsecond external electrode 130 peeled off the first end surface 110 eside and the second end surface 110 f side, and the solid electrolyticcapacitor was thus in a satisfactory state.

Comparing Examples 18 to 22 with Comparative Examples 9 to 13

Comparing the result of the Examples and that of the comparativeexamples, it has also confirmed through an experiment that providinginsulating resin body 110 with the first chamfered portion and thesecond chamfered portion and providing the first external electrode andthe second external electrode so as to cover the first chamfered portionand the second chamfered portion, can suppress peeling of the firstexternal electrode and the second external electrode off an end surfaceside of the insulating resin body in which a capacitor element isburied.

Thus in solid electrolytic capacitor 100 according to the embodiment,first external electrode 120 extending across first connecting portion1101, second connecting portion 1102, fifth connecting portion 1105, andsixth connecting portion 1106 and extending along the first and secondchamfered portions can alleviate a stress acting on first externalelectrode 120 at a boundary between first end surface 110 e and firstand second main surfaces 110 a and 110 b and enhance adhesion of firstexternal electrode 120 to a surface of insulating resin body 110 on theside of first end surface 110 e. This can increase adhesion strength offirst external electrode 120 and suppress peeling of first externalelectrode 120 off the insulating resin body at the time of formation orafter production. As a result, solid electrolytic capacitor 100 can beimproved in reliability.

Furthermore, second external electrode 130 extending across thirdconnecting portion 1103, fourth connecting portion 1104, seventhconnecting portion 1107, and eighth connecting portion 1108 andextending along the first and second chamfered portions can alleviate astress acting on second external electrode 130 at a boundary betweensecond end surface 110 f and first and second main surfaces 110 a and110 b and enhance adhesion of second external electrode 130 to a surfaceof insulating resin body 110 on the side of second end surface 110 f.This can increase adhesion strength of second external electrode 130 andsuppress peeling of second external electrode 130 off the insulatingresin body at the time of formation or after production. As a result,solid electrolytic capacitor 100 can be improved in reliability.

While in the embodiment described above a case has been described inwhich on the first end surface 110 e side, first connecting portion 1101and second connecting portion 1102 are provided with the first chamferedportion and fifth connecting portion 1105 and sixth connecting portion1106 are provided with the second chamfered portion by way of example,this is not exclusive and it suffices that at least first connectingportion 1101 and second connecting portion 1102 are provided with thefirst chamfered portion. In that case, it suffices that first externalelectrode 120 is provided to extend from at least first end surface 110e to first main surface 110 a and second main surface 110 b across firstconnecting portion 1101 and second connecting portion 1102. Thisconfiguration also allows first external electrode 120 to extend alongthe first chamfered portion and can thus enhance adhesion between firstexternal electrode 120 and insulating resin body 110 and suppresspeeling of first external electrode 120.

Similarly, While in the embodiment described above a case has beendescribed in which on the second end surface 110 f side, thirdconnecting portion 1103 and fourth connecting portion 1104 are providedwith the first chamfered portion and seventh connecting portion 1107 andeighth connecting portion 1108 are provided with the second chamferedportion by way of example, this is not exclusive and it suffices that atleast third connecting portion 1103 and fourth connecting portion 1104are provided with the first chamfered portion. In that case, it sufficesthat second external electrode 130 is provided to extend from at leastsecond end surface 110 f to first main surface 110 a and second mainsurface 110 b across third connecting portion 1103 and fourth connectingportion 1104. This configuration also allows second external electrode130 to extend along the first chamfered portion and can thus enhanceadhesion between second external electrode 130 and insulating resin body110 and suppress peeling of second external electrode 130.

Note that, as in the embodiment, by providing first connecting portion1101 and second connecting portion 1102 with the first chamfered portionand providing fifth connecting portion 1105 and sixth connecting portion1106 with the second chamfered portion, and providing first externalelectrode 120 to extend from first end surface 110 e across firstconnecting portion 1101, second connecting portion 1102, fifthconnecting portion 1105, and sixth connecting portion 1106 to first andsecond main surfaces 110 a and 110 b and first and second side surfaces110 c and 110 d, first external electrode 120 can be more firmly adheredto insulating resin body 110. By also configuring the second end surface110 f side to be similar to the first end surface 110 e side, secondexternal electrode 130 can be more firmly adhered to insulating resinbody 110.

In the description of the embodiment described above, combinableconfigurations may be combined with each other.

While the present invention has been described in embodiments, it shouldbe understood that the embodiments disclosed herein are illustrative andnon-restrictive in any respect. The scope of the present invention isdefined by the terms of the claims, and is intended to include anymodifications within the meaning and scope equivalent to the terms ofthe claims.

What is claimed is:
 1. A solid electrolytic capacitor comprising: atleast one capacitor element including an anode portion composed of ametal layer extending in a first direction and having an externalsurface with a plurality of recesses, a dielectric layer on the externalsurface of the metal layer, and a cathode portion having a solidelectrolyte layer on the dielectric layer and a current collector layeron the solid electrolyte layer; a leading conductor layer electricallyconnected to the current collector layer; an insulating resin bodycovering the capacitor element and the leading conductor layer, theinsulating resin body having a first end surface and a second endsurface opposite to each other along a first direction; a first externalelectrode including at least one first plating layer on the first endsurface, the at least one first plating layer being directly connectedto the leading conductor layer; and a second external electrodeincluding at least one second plating layer on the second end surface;the at least one second plating layer being directly connected to themetal layer: the insulating resin body including: (a) a first insulatingresin body having the leading conductor layer on a surface thereof, anda second insulating resin body on the first insulating resin body so asto cover the leading conductor layer and the plurality of capacitorelements, the second insulating resin body having a differentcomposition than the first insulating resin body; (b) a first mainsurface and a second main surface opposite to each other in a seconddirection orthogonal to the first direction, and a first side surfaceand a second side surface opposite to each other in a third directionorthogonal to the first direction and the second direction; (c) a firstconnecting portion connecting the first end surface and the first mainsurface, a second connecting portion connecting the first end surfaceand the second main surface, a third connecting portion connecting thesecond end surface and the first main surface, and a fourth connectingportion connecting the second end surface and the second main surface;the first connecting portion, the second connecting portion, the thirdconnecting portion, and the fourth connecting portion each have a firstchamfered portion; wherein: the first external electrode is formed alongthe first end surface and the first chamfered portions of the firstconnecting portion and the second connecting portion; and the secondexternal electrode is formed along the second end surface and the firstchamfered portions of the third connecting portion and the fourthconnecting portion.
 2. The solid electrolytic capacitor according toclaim 1, wherein: the at least one first plating layer includes a firstCu-containing layer on the first end surface, a second Ni-containinglayer on the first layer, and a third Sn-containing layer on the secondlayer; the at least one second plating layer includes a fourthCu-containing layer on the second end surface, a fifth Ni-containinglayer on the fourth layer, and a sixth Sn-containing layer on the fourthlayer.
 3. The solid electrolytic capacitor according to claim 1, whereinthe metal layer contains Al.
 4. The solid electrolytic capacitoraccording to claim 3, wherein the dielectric layer is an oxide of Al. 5.The solid electrolytic capacitor according to claim 1, furthercomprising an insulating resin layer different in composition from theinsulating resin body covering an external surface of the dielectriclayer on a portion of the metal layer free of the solid electrolytelayer and on a side of the second end surface.
 6. The solid electrolyticcapacitor according to claim 5, wherein a length of the insulating resinlayer in the first direction is equal to or greater than a length of theinsulating resin body in the first direction multiplied by 0.025 andequal to or less than the length of the insulating resin body in thefirst direction multiplied by 0.5.
 7. The solid electrolytic capacitoraccording to claim 5, wherein the insulating resin layer has a thicknessof 5 μm to 30 μm.
 8. The solid electrolytic capacitor according to claim5, wherein the insulating resin layer includes polyimide resin orpolyamideimide resin.
 9. The solid electrolytic capacitor according toclaim 1, wherein: the at least one capacitor element is a plurality ofcapacitor elements; the plurality of capacitor elements are stacked in asecond direction orthogonal to the first direction such that mutuallyadjacent capacitor elements have their respective current collectorlayers electrically connected to each other; and the current collectorlayer of only one capacitor element of the plurality of capacitorelements that is adjacent to the leading conductor layer is electricallyconnected to the leading conductor layer.
 10. The solid electrolyticcapacitor according to claim 1, wherein the first end surface and thesecond end surface each have a surface roughness of 2.2 μm to 8.3 μm.11. A solid electrolytic capacitor comprising: at least one capacitorelement including an anode portion composed of a metal layer extendingin a first direction and having an external surface with a plurality ofrecesses, a dielectric layer on the external surface of the metal layer,and a cathode portion having a solid electrolyte layer on the dielectriclayer and a current collector layer on the solid electrolyte layer; aleading conductor layer electrically connected to the current collectorlayer; an insulating resin body covering the capacitor element and theleading conductor layer, the insulating resin body having a first endsurface and a second end surface opposite to each other along a firstdirection; a first external electrode including at least one firstplating layer on the first end surface, the at least one first platinglayer being directly connected to the leading conductor layer; and asecond external electrode including at least one second plating layer onthe second end surface, the at least one second plating layer beingdirectly connected to the metal layer; the insulating resin bodyincluding: (a) a first insulating resin body having the leadingconductor layer on a surface thereof, and a second insulating resin bodylocated on the first insulating resin body so as to cover both theleading conductor layer and the plurality of capacitor elements, thesecond insulating resin body having a different composition than thefirst insulating resin body; (b) a first main surface and a second mainsurface opposite to each other in a second direction orthogonal to thefirst direction, and a first side surface and a second side surfaceopposite to each other in a third direction orthogonal to the firstdirection and the second direction; c) a first connecting portionconnecting the first end surface and the first main surface, a secondconnecting portion connecting the first end surface and the second mainsurface, a third connecting portion connecting the second end surfaceand the first main surface, and a fourth connecting portion connectingthe second end surface and the second main surface; the first externalelectrode extending from at least the first end surface to the firstmain surface and the second main surface across the first connectingportion and the second connecting portion; wherein: the second externalelectrode extends from at least the second end surface to the first mainsurface and the second main surface across the third connecting portionand the fourth connecting portion; and the first connecting portion, thesecond connecting portion, the third connecting portion, and the fourthconnecting portion each have a first chamfered portion.
 12. The solidelectrolytic capacitor according to claim 11, wherein: the insulatingresin body has a fifth connecting portion connecting the first endsurface and the first side surface, a sixth connecting portionconnecting the first end surface and the second side surface, a seventhconnecting portion connecting the second end surface and the first sidesurface, and an eighth connecting portion connecting the second endsurface and the second side surface; the first external electrodeextends from the first end surface across the first connecting portion,the second connecting portion, the fifth connecting portion, and thesixth connecting portion to the first and second main surfaces and thefirst and second side surfaces; the second external electrode extendsfrom the second end surface across the third connecting portion, thefourth connecting portion, the seventh connecting portion, and theeighth connecting portion to the first and second main surfaces and thefirst and second side surfaces; and the fifth connecting portion, thesixth connecting portion, the seventh connecting portion, and the eighthconnecting portion each have a second chamfered portion.
 13. A solidelectrolytic capacitor comprising: at least one capacitor elementincluding an anode portion composed of a metal layer extending in afirst direction and having an external surface with a plurality ofrecesses, a dielectric layer on the external surface of the metal layer,and a cathode portion having a solid electrolyte layer on the dielectriclayer and a current collector layer on the solid electrolyte layer; aleading conductor layer electrically connected to the current collectorlayer; an insulating resin body covering the capacitor element and theleading conductor layer, the insulating resin body having a first endsurface and a second end surface opposite to each other; a firstexternal electrode including at least one first plating layer on thefirst end surface and electrically connected to the leading conductorlayer; and a second external electrode including at least one secondplating layer on the second end surface and electrically connected tothe metal layer, wherein a plurality of conductive particles are presentin each of the first end surface and the second end surface.
 14. Thesolid electrolytic capacitor according to claim 13, wherein theconductive particles include Pd.
 15. A solid electrolytic capacitorcomprising: at least one capacitor element including an anode portioncomposed of a metal layer extending in a first direction and having anexternal surface with a plurality of recesses, a dielectric layer on theexternal surface of the metal layer, and a cathode portion having asolid electrolyte layer on the dielectric layer and a current collectorlayer on the solid electrolyte layer; a leading conductor layerelectrically connected to the current collector layer; an insulatingresin body covering the capacitor element and the leading conductorlayer, the insulating resin body having a first end surface and a secondend surface opposite to each other; a first external electrode includingat least one first plating layer on the first end surface andelectrically connected to the leading conductor layer; a second externalelectrode including at least one second plating layer on the second endsurface and electrically connected to the metal layer; a first platingfilm containing Zn covering an end surface of the metal layer at thesecond end surface; and a second plating film containing Ni covering thefirst plating film, wherein the first plating film and the secondplating film are positioned between the second external electrode andthe metal layer such that the second external electrode is indirectlyelectrically connected to the metal layer.
 16. A solid electrolyticcapacitor comprising: at least one capacitor element including an anodeportion composed of a metal layer extending in a first direction andhaving an external surface with a plurality of recesses, a dielectriclayer on the external surface of the metal layer, and a cathode portionhaving a solid electrolyte layer on the dielectric layer and a currentcollector layer on the solid electrolyte layer; a leading conductorlayer electrically connected to the current collector layer; aninsulating resin body covering the capacitor element and the leadingconductor layer, the insulating resin body having a first end surfaceand a second end surface opposite to each other; a first externalelectrode including at least one first plating layer on the first endsurface and electrically connected to the leading conductor layer; and asecond external electrode including at least one second plating layer onthe second end surface and electrically connected to the metal layer,wherein the insulating resin body has a first main surface and a secondmain surface opposite to each other in a second direction orthogonal tothe first direction, and a first side surface and a second side surfaceopposite to each other in a third direction orthogonal to the firstdirection and the second direction; the insulating resin body has afirst connecting portion connecting the first end surface and the firstmain surface, a second connecting portion connecting the first endsurface and the second main surface, a third connecting portionconnecting the second end surface and the first main surface, and afourth connecting portion connecting the second end surface and thesecond main surface; the first external electrode extends from at leastthe first end surface to the first main surface and the second mainsurface across the first connecting portion and the second connectingportion; the second external electrode extends from at least the secondend surface to the first main surface and the second main surface acrossthe third connecting portion and the fourth connecting portion; thefirst connecting portion, the second connecting portion, the thirdconnecting portion, and the fourth connecting portion each have a firstchamfered portion, the first chamfered portion has a curved shape in across-sectional view with respect to the third direction, and a firstradius of curvature of the first chamfered portion of the first andthird connecting portions is larger than a second radius of curvature ofthe first chamfered portion of the second and fourth connectingportions.
 17. A solid electrolytic capacitor comprising: at least onecapacitor element including an anode portion composed of a metal layerextending in a first direction and having an external surface with aplurality of recesses, a dielectric layer on the external surface of themetal layer, and a cathode portion having a solid electrolyte layer onthe dielectric layer and a current collector layer on the solidelectrolyte layer; a leading conductor layer electrically connected tothe current collector layer; an insulating resin body covering thecapacitor element and the leading conductor layer, the insulating resinbody having a first end surface and a second end surface opposite toeach other; a first external electrode including at least one firstplating layer on the first end surface and electrically connected to theleading conductor layer; and a second external electrode including atleast one second plating layer on the second end surface andelectrically connected to the metal layer, wherein the insulating resinbody has a first main surface and a second main surface opposite to eachother in a second direction orthogonal to the first direction, and afirst side surface and a second side surface opposite to each other in athird direction orthogonal to the first direction and the seconddirection; the insulating resin body has a first connecting portionconnecting the first end surface and the first main surface, a secondconnecting portion connecting the first end surface and the second mainsurface, a third connecting portion connecting the second end surfaceand the first main surface, and a fourth connecting portion connectingthe second end surface and the second main surface; the first externalelectrode extends from at least the first end surface to the first mainsurface and the second main surface across the first connecting portionand the second connecting portion; the second external electrode extendsfrom at least the second end surface to the first main surface and thesecond main surface across the third connecting portion and the fourthconnecting portion; the first connecting portion, the second connectingportion, the third connecting portion, and the fourth connecting portioneach have a first chamfered portion, the first chamfered portion has acurved shape in a cross-sectional view with respect to the thirddirection; the insulating resin body includes a first insulating resinportion on a side of the first main surface and which defines the firstmain surface and a second insulating resin portion on a side of thesecond main surface and which defines the second main surface; thesecond insulating resin portion is made of a material harder than thatof the first insulating resin portion; and the first chamfered portionof the first and third connecting portions is rounder than the firstchamfered portion of the second and fourth connecting portions.